1. Field of the Invention
This invention relates to an apparatus for observing the refractories of a furnace or the like, such as a coke oven, blast furnace, metal mixer, melting pot, converter, or vacuum degasifier, with a view to examining them for wear or damage.
2. Description of the Related Art
Generally, the refractory lining of a furnace or the like, such as a coke furnace, blast furnace, metal mixer, melting pot, converter, or vacuum degasifier, is gradually worn away during operation. Hence the necessity for the refractories to be observed to monitor the wear or damage before they become so thin that they can no longer stand operation.
Conventionally, the degree of wear or damage the refractories of a hot furnace have been determined with an apparatus having a camera of a double-water-cooling structure in which cooling air is blown into the camera chamber.
However, in the conventional observing apparatus, equipped with a camera having a double-water-cooling structure in which cooling air is simply blown into the camera chamber, the interior of the camera can suffer damage due to the radiation entering the apparatus and heating it through the glass window thereof when used in a space at a high temperature of 900.degree. C. or more. In addition, the automatic diaphragm of commercial cameras only provides a narrow permissible temperature range of 900.degree. to 1200.degree. C., so that observation cannot be performed to a satisfactory degree.